Various AC or DC operated electronics circuitry, such as high-quality audio equipment or sensitive measuring instruments, face increasing problems from external signal influences (particularly wire-bound from the AC mains supply but also wireless from all sorts of HF signals). At the same time, due to progress in circuit understanding and parts availability, higher performance equipment could be built—if there were a matching improvement in the power supplies.
However, common switching power supplies provide unwanted interfering signals, while traditional linearly regulated power supplies, both serial and shunt versions, have limited performance. Also, particularly in high-end audio, prior art designs have degrading effects on sound quality.
Attempts are known to use shielding techniques together with a rechargeable battery approach to overcome the above-mentioned drawbacks. However, such devices are costly to build and are not very suitable for instruments in continuous use or with a significant power demand.